Free sample MARC data

Might be useful for testing:

University of Michigan Libraries - Open Access Bibliographic Records - MARC21 binary, MARCXML
Open Access für Daten aus dem SWB - MARC21
Open Library Data - Records that have been contributed to Open Library from different sources
Project Gutenberg Australia - "details of the 'Australiana' ebooks at Project Gutenberg Australia"
E-Discover the Classics - "Nearly 500 Downloadable Classics from Project Gutenberg through your Library Catalog. Includes the most popular downloaded e-books such as Pride and Prejudice, The Time Machine, A Christmas Carol, Jane Eyre and many more!"